More recently, antibodies which block the negative immune regulatory programmed cell death protein 1 (PD-1), pembrolizumab, was approved by the FDA to treat patients with metastatic or unresectable MSI tumours (including MSI GC) as well as patients with metastatic, recurrent or locally advanced GC that expresses PD-L1 and have progressed despite two or more systemic treatments (Fashoyin-Aje et al. 2019). The gene discussed is PDCD1; the disease is neoplasm.